Series of new cobalt (II) and nickel (II) trinuclear fluorotrifluoroacetates with tetrahydrofuran – contribution to the inverse coordination chemistry and unique cations

Abstract The six new trinuclear fluorocarboxylates with tetrahydrofuran (THF) molecules as terminal ligands are presented. The structures of compounds have been determined by single-crystal X-ray diffraction. According to the structure data, complexes of nickel (II) and cobalt (II) form isomorphous series, namely [K(CF 3 COOH) 6 ][M 3 (μ 3 -F)(CF 3 COO) 6 (THF) 3 ] (M = Co ( I ) and Ni ( II )), Na[M 3 (μ 3 -F)(CF 3 COO) 6 (THF)(CF 3 COOH) 2 ] (M = Co ( III ) and Ni ( IV )) and [Li(CF 3 COOH) 4 ][M 3 (μ 3 -F)(CF 3 COO) 6 (THF) 3 ] (M = Co ( V ) and Ni ( VI )). In crystal structures of I , II , V and VI , previously unknown cations [K(CF 3 COOH) 6 ] + and [Li(CF 3 COOH) 4 ] + have been detected. All substances were studied by IR spectroscopy, and bands sensitive to the nature of metal atoms included in the compounds have been found. The inverse coordination of tridentate fluoride-ion in cobalt (II) and nickel (II) fluorocarboxylates is discussed in the article.